Spring clutch



Jupe 10, 11930. c. STARKEY 1,762,799

" SPRING CLUTCH Filed F'eb. '7, 1927 'l Jiffa.I

` melted .lune` 1o, 1930 UNITED STATES PnurlaN'rV oFFl-CE.

WILLIAM cABLE'ToNs'rAaxEY, oP ALLIsoNvILLE, INDIANA, AssIeNon 'ro I.. e. s. DEvIcEs conPoaA'rIoN, or INDIANAPOLIS, INDIANA, A coRPoRArIoN or INDIANA SPBIN G I Application led February It is the object of'my invention to produce a clutch, particularly va uni-directional clutch, which will operate to clutch together two relativel rotatable members when one member obtalns a predetermined velocity' of rotation or when one 'member undergoes greater than a predetermined angular acceleration. a

I accomplish the above objects by providing one of the relatively rotatable members with an axial recess in which I locate a coil spring operatively connected to the other rotatable member, such coil spring being normally slightly smaller in diameter than its associated recess; and, in the case where my clutch is controlled by rotational speed,

I ,provide means responsive to .centrifugal force for subjecting the spring to a torque to cause it to expand and grip the wall of its 2o associated recess when a predetermined rotational speed is reached. When I= wish my clutch controlled by acceleration, I may connect the coil spring solas to rotate withthat rotatable member the acceleration of which is to control the operation of the clutch; and

through the` coil spring, I connect to `such rotatable members an inertia weight, so that when a given acceleration occurs the spring will be subjected t`\a torque suiiicient to cause it to expand 'and rip the wall ofthe recess in the other rotatable member. The accompanying drawing illustrates my invention: Fig. 1 is a longitudinal section through a clutch controlled in accordance with rotationalvelocity; Fig. 2vis an end elevation of such a clutch; Fig. 3 is a longitudinal section througha trolleyretriever embodying a clutch controlled both byacceleration and velocity; and Fig. 4 is a transverse section on the line 4-4 of Fig. 3.

In the device illustrated in Figs. 1 and 2, my clutch is illustrated as operating between a driven member such as the ear 10 and a driving member'such as the s aft 11 of an electric motor 12. Thisshowing isl merely by way of example, as my clutch is capable of use in diiferent situations.

Rotatable with the shaft 11 is .a clutch member in the form of a cup 13 which enters 50 the counterbored portion of the hub 14 of CLUTCH 7, 1927. yserial No. 166,2so.

the gear 10 and is conveniently held in place therein by means of the split spring 'ling 15. The bore proper of the hub 14 has a diam. eter equal to the internal diameter of the cup 13.; so that the inner face' of the gear hub 55 and the in nerv -face of the cup form a substantially continuous 'cylindrical surface.

Within the cup 13 and the bore of the gear.v hub 14 is located a helical coil spring 17 having normally a diameter somewhat small- 30 fer than the internal diameter of the cup and gear.- The spring 17- is Aoperatively connected, as by means of av pin 18, to t e cu 13 so that it .rotateswith such cup and wit the shaft 11. The other end of -the'spring 65 17 is operatively connected'to a sleeve 20 which is rotatable, at least through a small an" le, relative to the shaft 11.`

n the outer face of the sleeve 20 is a pivotally mounted pawl 2l connected to a 'zo spring 22 Awhich normally serves to hold the pawl inward and out of engagement with co-operatingl ratchet teeth 23 on the gear 11.'

Since the spring 17 is normally slightly smaller Ithan the recess in which it is lo- 75 cated, free relative rotation'of the gear 10 and shaft 11 may occur. When, however, lthe shaft 11, which carries with it the cup 13 and spring 17, reaches a rotational lspeed such that the centrifugal force of the pawl 30 21 will cause such pawl to move outward against the force of the spring 22 suiiciently far to engage one of thev teeth 23, a torque is immediately imposed upon the spring; for, under such circumstances, one end of g5 the spring is connected to the driving shaft 11, andthe other, by reason of the 4engagement of the pawl 21 with one of the teeth 23, becomes connected to the gear` 10. This l torque has a tendency to unwind the spring 9o and increase its diameter, thus causing 1t to. expand and grip vfirmly the inner walls of the cup 13 and gear hub 14 to clutch suchtwo lparts together.

The trolley retriever illustrated in, Figs.vr 9 5 3 and 4 comprises a stationary member 30 having a pro]ec ting stud shaft 31 on'which is rotatably mounted a spool 32 for a cable 3 3. A coil spring34 operating. between the shaft 31 and the spool 32 tends to rotate the 10Q spool in the direction to cause the cable to be wound up on it.

The spool 32 is counter-bored to receive" y`an annular-flange 35 on the stationary member 30. The internal diameter-of this iange is substantially equal to that of the bore of the spool 32, so that the inner face of the flange '35"aud spool 32 form asubstantially `continuous cylindrical surface.

39 which is adjacent the stationary member 30, an inwardly spring-pressed pawl 40 may' be mounted, such pawl beingfarranged to move outwardly and engage one of a series of teeth 41 on the plate 30 whenever the centrifugal force of the pawl is sufficient to overcome the spring-pressure tending to move it inwardly.

I-n the device just described, the spring 38` normally` has a diameter somewhat smaller than the internal diameter of the Hange 35. As a result, the spool 32 is normally free to rotate, and the spring 34 operates to take up any slack in the cable 33. If the cable 33 is subjected to va strong outward pull causing a rapid rotation of the spool 32, the inertia of the weight 39 causes a 4torque to be imposed on the spring 38; and when vsuch torque becomes sufficient to expand the spring into engagement with the inner surface of the flange 35, the spool 32 is locked to theplate 30 and further rotation permitting unwinding of the cable 33 is prevented. If the acceleration of the spool 32 is gradual and insuticient to cause expansion of the spring 38 into gripping engagement with t e flange 35, but if the spool eventually obtains an excessive rotational speed, then the pawl 40 will move outward and engage one of the teeth 41 thus stopping rotation of the weight 39. This action imposes a torque on the spring 38, such torque operating to cause the spring to expand and to grip the inner face of the flange 35 to lock the spool 32 to the plate 30.

The weight 39 may be used in connection withv a device of the type illustrated in Figs. l and 2 if it is desired to have the clutch operate in response to acceleration. This result may be accomplished by increasing the mass of the sleeve 20, or a corresponding part, to a point where its inertia will be sufficient to change the diameter of the spring.

In oth of the devices shown, operation of the spring is dependent upon rotation of the sprin This is necessary when it is desired that t e spring expand as a result of inertia forces transmitted through the spring, but it gagement with spring is" expanded is nearly entirely taken at the surface of-the spring, and the parts whichl cause the spring to expand into en-y gagement with `the wall of its associated recess only c arry a very small portion of the torque. -As a result, those parts such as the pawls 21 and 40, teeth- 23 and 41, and bushing or sleeve 20 need not have any great strength.

I claim as my invention 1. In combination, two relatively rotatable members,one of said members having an axial recess, a coil spring located in said recess and having one end operatively connected to the.l other of said members, said coil spring having a normal external diamn eter less than the diameter of said recess, a movable pawl rotatable with said coil spring, means tending to hold said pawlK inward against the action of centrifugal force as said spring is rotated, and one or more teeth on said recessed member adapted to be engaged by said pawl as it moves outward under the influence of centrifugal force when said .spring reaches ,a predetermined rotational speed.

2. In combinationl, two relatively rotatable members, one of said members having an axial1 recess, a coil spring located in said recess, said spring being normally free from engagement with the circumferential wall of said recess, said spring being operatively connected at one end to one of said members, and means operative unopposed by said spring to connect the other end of said spring to said recessed member when one of said members reaches a predetermined rotational speed, whereby the torque transmitted through said spring from one member to the other will cause saidspring to unwind and expand into iirm frictional ene the wall of its associated recess.

' 3.'I n combination, two relativel rotatable members, one of said members aving an axial recess, a coil spring located in said recess, said spring being normally free from engagement with the circumferential wall of vsaid recess, said spring being operatively connected at one end to one of said members, and means operative unopposed by said spring to connect the other end ofl said spring to said recessed member when said spring reaches a predetermined rotational speed, whereby the torque transmitted through said spring from one member to the other will cause said spring to unwind and expand into firm frictional engagement with the wall of its associated recess.

4. In combination, two relatively rotatable 55 recess and'havin nected to the et er of said members, said members, one of said members havin -an axial recess, a weight yrotatably mounte jcoaxially 4with said'members', a coil spring located in the recess in'said recessed meinber rand having one end connected toythe other' member and the 'other `end to said" weight, said sprin't being. normally free from engagement with the wall of its asso-VA ciated recess but being Vcapable of expanding into frictional engagement with such wall 'under' the i-n-.tluence oftorque imposed on the spring due to rotationalacceleration of that membento'which the spring is operatively eennected.

5. In combination, two relatively rotatable members, one of said members having an axial recess, al cil spring located in said recess and operatively connected to the other of said members, and means operative when said spring is subjected to la predetermined angular'accelerat-ion for imposing onv said spring a torque'causing it partially to .un-

wind into gripping engagement with the wall of itsa'ssociated recess.

y 6. In combination,- two relatively rotatable members, one of said members having an axial recess, a coil spring located in said recess and o erativel connected to the other of said mem ers, an means operative when `one ofsaid members is subjected to a predetermined angular accel'eration for impos-l I ing on said spring a torque causing it par- 4' velocity for connecting said spring to said recessed member, whereby the torque transferred through said spring from one member to the other will cause said ring to uns wind and expandinto firm frictional en- 50 gagement with thel wall' of its associated- 8. In combination, two relativelyt rotatable members, one of said members aving an axial recess, a coil 'spring located in -said one en operativelycon.-

gcoil slp'ring having a normal external diameter ess than the diameter of .said recess, and means operative unopposed by said n ao sprin when said spring 'reaches a predetermine rotational velocity for connecting said Aspring Vto said recessed member, whereby th torque transmitted through said sp from one membe'i to the other will 65 cause said spring to unwind and expand maar vassociated recess.

spring' into irm rictional engagement. with lthe wall; of its associated recess.

axial recess, a coil sprin located in. said recess and having'one en operatively con nected to the other of said 'members, said coil s ring having a normal external diameter ess than the diameter of said recess, and means 'operative by centrifugal--force and u'iopposedby said spring when one of said mem ers reaches ;a' predetermined rotational velocity for connecting said spring tol said 'recessed memberfwhereby-the' torque v transmitted through said spring from one memberto the other will-cause said spring to unwind and expand into firm jrictional engagement with the wall of its associated recess.

10. In combination, two relatively rotatable members, one of v said members having an axial recess, a coil spring located in said recess and having one end operatively con-v nected to v`the other of said members, said coil spring having a normal external diamef ter less than the diameter of said recess, and x means operative unop osed by said spring when one of said mem rs lreaches a predetermined rotational velocity for connecting said spring to said recessed member, whereby the torque transmitted throiirh said springfrom one member tothe ot er will cause said spring to unwind and ex' and into irm frictional engagement with t e wall of its associated recess. Y 11. In combination, a rotatable driving member, a rotatable driven member co-axial therewith, one of said members havingfan axial recess,'a coil spring located in said recess and operatively connected to the other of -said members, said coil being out of engagement with the circumferential surface-'of said recess, and means" operative unopposed by said springvwhen -said driving member reaches a predetermined rotational velocity for connecting said" spring to said recessed member whereby the torque transmitted through sai spring from one member to "the other will cause said spring to unwind and ex and 'into rm fric. 115 vthe wall of its tional engagement wit 12. In combination, tivo relatively rotatable members havingalined axial recesses,

a coil s ring located in said recesses, saidd eilig normally free' from engage.

ment with the wall of the recess in "one of said members andjbeing operatively connected tothe other'f-.of said members', and

means operative -when one of said members .reaches a predetermined rotational velocity for causing.v said' spring to expand` into grippingenga'gement with `the wall of the recess in that imember with which it is normally free 'from engagement'.` s

9. In combination, two relativel rotatable '.f

members, oneof said vmembers aving an" ring normally- 13. In combination, two relatively rotatable members, one of said members having antaxial recess, a coil spring located in said recess and o erativel connected to the other of said members, sai spring being normally free from connection with said recessed member, and means operative when one of said members is subjected tov a predetermined angular acceleration for connecting said spring to said recessed member whereb relative rotation of said members in one d1- rection will cause said spring partially to unwindinto gripping engagement with the wall of its associated recess.

14. In combination, two relatively rotatable members' having alined axial-recesses, a coil spring located in said recesses,`said spring being normally free vfrom engagement with the wall of,the recess in one 'of said members and being operatively connected to the other of said members, and means o erative when said. spring'reaches a pre etermined rotational .velocity for causing `said. spring to expand into gripping engagement with the wall of the recess in that member with which it is normally free from engagement.

15.'In combination, two relatively rotattermined rotational velocity, one o abutments being rotatable with said spring said abutments being rotatable with said spring and ther other being'rotatable with `recess and having one end operatively connected to the other of said members, said coil spring having a normal external diameter less than the diameter of said recess, and a pair of co-operating abutments normally disengaged from eachother but inter-engageable when said spring reaches a reded` Sal and fthe other being rotatable with said recessed member.

In l'witness whereof, I have hereunto set my hand at Indianapolis, Indiana, this 4th Y dayA of February, A. D. one thousand nine hundred and twenty seven.

WILLIAM CARLE'ION STARKEY.

able members having alined axial recesses,

a coil spring located in said recesses, said spring being normally free from engagement with the wall of' the Arecess in one of said members and being o eratively connected to the other 'of said mem ers, and means operative by centrifugal force when one of said members reaches a predetermined rotational y velocity for causing said 'spring to expand into gripping engagement with the wall of the recess in that member with which it is `normally free from engagement.

16. In combination, a rotatable driving member, a rotatable driven member coaxial therewith, said two members being provided with alined axial recesses, a coil spring located in said recesses, said spring being norvmally free from engagement wlth the wall ofthe recess in one of said members and A being operatively connected to the other of said members, and means operative when one of said members reaches a predetermined -rotational velocity fr causing said spring to expand into gripping engagement with the wall of the recess in that member with which'- it is normally free from engagement.

17. In combination, two relatively rotatable members,`one of said members having 'an axialrecess, a coil spring located in said recess and having. one end operatively condisengaged.- from each otherbut inter-en'- gageable when one of said members reaches a predetermined rotational velocity, one of 

